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Merge pull request #3751 from daniel-k/pr/samd21_i2c
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samd21/i2c: add feedback in case transfer failed
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@PeterKietzmann
PeterKietzmann committed Sep 29, 2015
2 parents 53d7443 + c747d7d commit d081ade
Showing 1 changed file with 26 additions and 23 deletions.
49 changes: 26 additions & 23 deletions cpu/samd21/periph/i2c.c
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Original file line number Diff line number Diff line change
Expand Up @@ -37,9 +37,9 @@
#define SAMD21_I2C_TIMEOUT (65535)

/* static function definitions */
static inline void _start(SercomI2cm *dev, uint8_t address, uint8_t rw_flag);
static inline void _write(SercomI2cm *dev, char *data, int length);
static inline void _read(SercomI2cm *dev, char *data, int length);
static inline int _start(SercomI2cm *dev, uint8_t address, uint8_t rw_flag);
static inline int _write(SercomI2cm *dev, char *data, int length);
static inline int _read(SercomI2cm *dev, char *data, int length);
static inline void _stop(SercomI2cm *dev);

/**
Expand Down Expand Up @@ -248,9 +248,9 @@ int i2c_read_bytes(i2c_t dev, uint8_t address, char *data, int length)
}

/* start transmission and send slave address */
_start(i2c, address, I2C_FLAG_READ);
if(_start(i2c, address, I2C_FLAG_READ) < 0) return 0;
/* read data to register */
_read(i2c, data, length);
if(_read(i2c, data, length) < 0) return 0;
_stop(i2c);
/* return number of bytes sent */
return length;
Expand All @@ -276,10 +276,10 @@ int i2c_read_regs(i2c_t dev, uint8_t address, uint8_t reg, char *data, int lengt
}

/* start transmission and send slave address */
_start(i2c, address, I2C_FLAG_WRITE);
if(_start(i2c, address, I2C_FLAG_WRITE) < 0) return 0;
/* send register address/command and wait for complete transfer to
* be finished */
_write(i2c, (char *)(&reg), 1);
if(_write(i2c, (char *)(&reg), 1) < 0) return 0;
return i2c_read_bytes(dev, address, data, length);
}

Expand All @@ -302,8 +302,8 @@ int i2c_write_bytes(i2c_t dev, uint8_t address, char *data, int length)
return -1;
}

_start(I2CSercom, address, I2C_FLAG_WRITE);
_write(I2CSercom, data, length);
if(_start(I2CSercom, address, I2C_FLAG_WRITE) < 0) return 0;
if(_write(I2CSercom, data, length) < 0) return 0;
_stop(I2CSercom);
return length;
}
Expand All @@ -329,11 +329,11 @@ int i2c_write_regs(i2c_t dev, uint8_t address, uint8_t reg, char *data, int leng
}

/* start transmission and send slave address */
_start(i2c, address, I2C_FLAG_WRITE);
if(_start(i2c, address, I2C_FLAG_WRITE) < 0) return 0;
/* send register address and wait for complete transfer to be finished */
_write(i2c, (char *)(&reg), 1);
if(_write(i2c, (char *)(&reg), 1) < 0) return 0;
/* write data to register */
_write(i2c, data, length);
if(_write(i2c, data, length) < 0) return 0;
/* finish transfer */
_stop(i2c);
return length;
Expand Down Expand Up @@ -367,7 +367,7 @@ void i2c_poweroff(i2c_t dev)
}
}

static void _start(SercomI2cm *dev, uint8_t address, uint8_t rw_flag)
static int _start(SercomI2cm *dev, uint8_t address, uint8_t rw_flag)
{
uint32_t timeout_counter = 0;

Expand All @@ -387,7 +387,7 @@ static void _start(SercomI2cm *dev, uint8_t address, uint8_t rw_flag)
&& !(dev->INTFLAG.reg & SERCOM_I2CM_INTFLAG_SB)) {
if (++timeout_counter >= SAMD21_I2C_TIMEOUT) {
DEBUG("STATUS_ERR_TIMEOUT\n");
return;
return -1;
}
}

Expand All @@ -400,19 +400,20 @@ static void _start(SercomI2cm *dev, uint8_t address, uint8_t rw_flag)
/* Check arbitration. */
if (dev->STATUS.reg & SERCOM_I2CM_STATUS_ARBLOST) {
DEBUG("STATUS_ERR_PACKET_COLLISION\n");
return;
return -2;
}
}
/* Check that slave responded with ack. */
else if (dev->STATUS.reg & SERCOM_I2CM_STATUS_RXNACK) {
/* Slave busy. Issue ack and stop command. */
dev->CTRLB.reg |= SERCOM_I2CM_CTRLB_CMD(3);
DEBUG("STATUS_ERR_BAD_ADDRESS\n");
return;
return -3;
}
return 0;
}

static inline void _write(SercomI2cm *dev, char *data, int length)
static inline int _write(SercomI2cm *dev, char *data, int length)
{
uint16_t tmp_data_length = length;
uint32_t timeout_counter = 0;
Expand All @@ -424,7 +425,7 @@ static inline void _write(SercomI2cm *dev, char *data, int length)
/* Check that bus ownership is not lost. */
if (!(dev->STATUS.reg & SERCOM_I2CM_STATUS_BUSSTATE(2))) {
DEBUG("STATUS_ERR_PACKET_COLLISION\n");
return;
return -2;
}

/* Wait for hardware module to sync */
Expand All @@ -438,19 +439,20 @@ static inline void _write(SercomI2cm *dev, char *data, int length)
&& !(dev->INTFLAG.reg & SERCOM_I2CM_INTFLAG_SB)) {
if (++timeout_counter >= SAMD21_I2C_TIMEOUT) {
DEBUG("STATUS_ERR_TIMEOUT\n");
return;
return -1;
}
}

/* Check for NACK from slave. */
if (dev->STATUS.reg & SERCOM_I2CM_STATUS_RXNACK) {
DEBUG("STATUS_ERR_OVERFLOW\n");
return;
return -4;
}
}
return 0;
}

static inline void _read(SercomI2cm *dev, char *data, int length)
static inline int _read(SercomI2cm *dev, char *data, int length)
{
uint32_t timeout_counter = 0;
uint8_t count = 0;
Expand All @@ -463,7 +465,7 @@ static inline void _read(SercomI2cm *dev, char *data, int length)
/* Check that bus ownership is not lost. */
if (!(dev->STATUS.reg & SERCOM_I2CM_STATUS_BUSSTATE(2))) {
DEBUG("STATUS_ERR_PACKET_COLLISION\n");
return;
return -2;
}

/* Wait for hardware module to sync */
Expand All @@ -477,13 +479,14 @@ static inline void _read(SercomI2cm *dev, char *data, int length)
&& !(dev->INTFLAG.reg & SERCOM_I2CM_INTFLAG_SB)) {
if (++timeout_counter >= SAMD21_I2C_TIMEOUT) {
DEBUG("STATUS_ERR_TIMEOUT\n");
return;
return -1;
}
}
count++;
}
/* Send NACK before STOP */
dev->CTRLB.reg |= SERCOM_I2CM_CTRLB_ACKACT;
return 0;
}

static inline void _stop(SercomI2cm *dev)
Expand Down

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